This is the inside of the turret (inverted):
A lot of details about the Monitor's design are in this article in the NY Times.
This is what I found fascinating: The War Department in 1861 opened a public competition to design a new class of warships. The designs had to be submitted in a month. They built the ship in four months. From one end to the other, it was a ship with new technologies and it was in combat a month after that.
The closest thing that I've heard to that was the first class of LSTs, which went from the beginning of design at BuShips to sea trials in less than a year. Over a thousand were built during the war. One of them is still working for a living.